"1. Fast streaming, everywhere, on phones and browsers" and "4. Good search and discovery experience" are the essentials (with 1 including the hosting requirements). Most users are ready to put up with moderate resolution videos, the content will accumulate surprisingly quickly as long as there is some initial content to draw people in, and it'll be good news for the platform when spam and copyright issues become actual problems. But feature 1 is big enough in cost and difficulty, to be a big barrier to entry by itself.
> 5. The ability to battle spams and handle external copyright claim to avoid lawsuit.
That's also vital. Otherwise you're risking your entire platform on lawsuits from film and music companies when copyrighted content is inevitably uploaded.
As I mentioned in the comment, this is sort of a "good" problem to have, in that both spammers and copyright claims look for popular, well-known services to focus their efforts on. The problems will definitely exist at small scales too, but compared to the other difficulties mentioned, these are much smaller concerns initially.
